Predictors for Unsuccessful Outcome of Lumbar Spinal Stenosis Surgery: A Secondary Analysis of the Two Randomized NORDSTEN Trials.

Abstract

Observational cohort study. To evaluate potential predictors of unsuccessful outcomes after surgery in patients with lumbar spinal stenosis (LSS). LSS is a common cause of disability in adults and the leading indication for spine surgery in Norway. Despite advances in surgical techniques, nearly one-third of patients report either minor or no improvement or worsening of symptoms after surgery. Identifying predictors of unsuccessful outcomes is essential for improving patient selection and shared decision-making. This secondary analysis used data from the two NORwegian Degenerative spondylolisthesis and spinal STENosis (NORDSTEN) randomized trials, which included 704 surgically treated patients with LSS, with (n=267) or without (n=437) degenerative spondylolisthesis. The Oswestry Disability Index (ODI) was the primary outcome measure. A reduction in ODI score of less than 30% from baseline to two years postoperatively was defined as an unsuccessful outcome. Multivariable logistic regression analysis was used to evaluate whether carefully selected baseline variables were associated with an unsuccessful outcome at two-year follow-up. Longer duration of radiating pain (>12 mo; OR=2.58, 95% CI 1.54-4.29), psychological distress (HSCL-25 ≥1.75; OR=1.60, 95% CI 1.01-2.53), and advanced disc degeneration (Pfirrmann grades 4-5; OR=1.98, 95% CI 1.26-3.12) were independently associated with an unsuccessful outcome. Commonly discussed factors such as age, BMI, smoking, ASA grade, and predominant back pain did not reach statistical significance for association with the outcome. Among patients undergoing surgery for LSS, longer symptom duration, psychological distress, and advanced disc degeneration were associated with a higher risk of unsuccessful postoperative outcomes.